ABSTRACT When older adults are hospitalized due to a major health event, the older adults and our healthcare system rely on an estimated 40 million family caregivers to assist their loved ones with self-care activities and complex medical and nursing tasks after hospitalizations. Despite acknowledgement that family caregivers are critical to patients and our healthcare system, caregivers report dissatisfaction with their identification and needs being met during the hospitalization process. In turn, caregivers feel ill-equipped to assist in tasks when their loved one returns home. Assessment of caregivers? needs, strengths, and resources during hospital care may be particularly important to inform and target training that will equip them to fulfill the needs of their loved ones at home. We propose to develop the Caregiver Hospital Assessment Tool (CHAT) which will identify family caregivers? needs and guide providers? clinical decision making for training during hospital care. As a result of this work, family caregivers can expect to receive recognition and meaningful training during the hospitalization of their loved one with the help of CHAT. CHAT will be developed based on the recommended caregiver assessment framework from the National Center on Caregiving at Family Caregiver Alliance and perspectives from collaborative partners that include family caregivers, leading aging and caregiving scientists, and healthcare providers and systems. Specifically, for Aim 1 we will develop CHAT and assess content validity from a panel of experts using quantitative methodology; for Aim 2 we will evaluate face validity of CHAT items from family caregivers using qualitative methodology; and for Aim 3 we will identify clinical utility and acceptability considerations from key stakeholders to inform further refinement of CHAT. To address these aims, we will use a convergent mixed methods approach. In Aim 1, we will survey family caregivers and leading aging and caregiving scientists to gauge feedback on content, wording, and response format. In Aim 2, we will administer CHAT and complete interviews with family caregivers to learn their perspectives on clarity and appropriateness of CHAT. In Aim 3, we will conduct focus groups with frontline providers and healthcare system administrators to inform the refinement of CHAT, including mechanisms for administering and interpreting CHAT, as well as barriers and facilitators to implementing CHAT into routine practice. Findings from all three aims will be synthesized to help strengthen the overall analysis and generate information to refine CHAT. The development and refinement of CHAT is critical to the next planned grant proposal which will examine dose of CHAT specified training and the effect of CHAT on family caregivers and older adults. We expect the refined and psychometrically grounded CHAT will lead to improved knowledge, skills, and abilities of family caregivers. Family caregivers that are well-prepared have the potential to increase their own well-being but also help improve health outcomes and preventable readmissions for their loved ones.